Has anyone done back to back testing on big cube race engines from a single 4 to a tunnel ram? My motors out with a spun bearing so thinking of more power but has to be worth the cost.

Can't speak for the big cube part of the question, but years ago 2-650's vs a 750 single on a 446cu.in. was worth about 3-4 mph in the 1/4.

I'm tunnel rams on everything now 493 & 528 cu.in.

I picked up 40+ hp

Depends on the quality of the two combos. If you are getting serious HP from a very good single dominater setup, it might only be worth about 20 HP on an original 800 HP motor . Have anything wrong with the new t ram and carbs, and it might even go backwards. So it is a risk, no guarantees.

i have on both race motors and pump gas Hi PO (above 600 HP) street motors, every time I increased the air and fuel flow the HP on the engine dyno went up, from 30 to 65 HP gain depending on the motor and heads, At the 1/4 mile tracks the ET and MPH got better also, going from a single four barrel carb and intake to a six pack and later to a tunnel ram and two 850 CFM 4150 carbs with no other changes went quicker and faster, .2 tenths on the pump gas six pack motors and more on the race gas bracket motors with dual dominator carbs
What are your plans on the intake and carb size and brand?

Research "Engine Masters", they love TR's and have Dyno numbers with comparisons to back up their claims.

Not quite back to back but we switched from a well sorted Pro Systems 1050 on an Indy 440-3X to an Indy T/R with 2 x 1150 Gen 3 Dominators, from one season to the next.
This is on a 580 engine (4.53 x 4.5). Best to best the difference is only 0.06 in favour of the T/R. However the single only ever ran in the 9.50's once (9.57 @ 142.7) and was used for 8 seasons, the T/R has dozens of 9.50 passes (9.51@142.5 best) and has been on from 2017. Best MPH has always been around 142 with both but the T/R has carded a lot more in that region.
The other caveat is the car had an extra 100lb + added a season or so before the T/R was fitted, Then, the 1 x 4 was normally running around the bottom 9.7's with a best of 9.6 something.
The car is 4023lb w/d last time we weighed it. Wallace would calculate the 1 x 4 at around 880 hp and the 2 x 4 920 hp, again best to best. Unfortunately I can't back it up as the 580 motor has never been dyno'd.
I'm pretty sure the T/R carbs are too big for the engine and it may run quicker with smaller carbs but after a season of tweaking they run well, they were originally specified for a 655 which we "borrowed" them from so they won't be changed.
On this engine I would have likely done the swap even if I didn't have the T/R and carbs already but with 1050's. I do like the look of a T/R but the cost of swapping would now be $3500+, though you might get back $1500 for the single stuff. So is the "maybe" 40 hp worth $2K ? Not the best hp per $ return I know but we did pick up something

HTH's

If the 4 barrel was better the Pro Stock guys would have used it

There were two conclusions Engine Masters leaned too as to why TR single vs dual always performed best on a dyno, greater cfm was not one, but straighter air flow out of the base of the carb, and better inherent fuel distribution issues.

I agree. Been running a T ram on the street for a few seasons now. All i can say is if your gonna do it for ET, use a sheet metal t ram. The cast units weight a ton. I probably added 35-40# to the car. I only ran it at the track 1 time. I was down 2mph and 2 tenths in the 1/8 and the 1/4 compared to a single 1150 Dominator. I did have a humid day when i last went with the T ram and the added weight with exhaust vs no exhaust with Dominator i'm sure it was very close to 100# added and the bad air day on top of that. Flip side is they run great on the street once properly built/tuned. Easy start up without throttling it and will idle in traffic all day and stay clean. I always say better than fuel injection. Next time out i will be sure to leave the exhaust at home and pic a good air day.

Are your sure that your fuel supply system is good enough for your motors requirements? Can you slow the 1/4 mile MPH down by jetting it richer? If not, maybe you need to make the fuel supply system better

Yes and Yes, it was all upgraded after I was chasing a fueling issue. I'd guess if I can slow down a 655ci 7400rpm motor by installing too big a main jet, I think the fuel system is up to it

So the motor is 596 Predator engine with a 1250 APD with E85 on Indy's single 4. Dynoed at 1060 on engine and 9.4's at 145 nearly every pass. 3880lb Cuda with me in it. While the motor is out probably goimg to go a bigger cam and fuel injection on a Indy cast tunnel ram. Very expensive but. Have been chasing lean and rich condiotions from one bank to the other with the single 4 so thinking direct port injectors would solve that (but expensive)

How high can you get the injectors, to help realize the cooling E85 offers you?

Just thinking out loud but there's no real need to go to a T/R, injectors will solve the fuel distribution issues on the single plane.

EFI, especially the better ones, can help you make the motor last longer and make more power as well.
My next blown motor will be EFI fuel injection with a Vortech centrifugal super charger
My current bracket, heads up motor (572 C.I. B1 KB aluminum block wedge motor) will have, I'm still assembling it and needing to buy the cam, a sheet metal tunnel ram on a set of B1 heads running two Mark Sullens prep Dominator E85 carbs and maybe adding two kits of NOS, shooting for 1000 to 1400 HP for some local heads no prep racing

Thankyou for all the replys. I think I will go with injection on my current manifold mainly because of gains compared to cost. I still street drive this car and the costs can get out of hand real quick. Thanks again

What you've been told here is basically what I was told several years ago when I was pondering doing the same thing. My hemi is pretty well sorted out w/ a single 4, but of course I was looking for more.
To me, it isn't worth what it'd cost to swap to a tunnelram. No matter how cool it looks, lol. Especially when the performance may not even come close to reflecting the cost. I think it'd be faster, but I'm not paying 3 grand or more for a tenth.

Youtube user Drag Boss Garage has some vintage Pro Stock tunnel ram info on there. You can see how the old school pro stock racers were modifying the plenum size down smaller and messing with the runner angles on those old cast aluminum tunnel rams bitd.

He is a Ford guy so it's almost all Ford engines, but the theory of what Bob Glidden and those guys were trying to do to make those work better should apply to any race engine.

EDIT:

Here is one of those videos. There is another one he has that also shows how they cut the runners and reworked the intake angles.

https://youtu.be/toBKoPEW0BU?si=PcINUr31R3F-LxDP